I have used a Nikon D40x for years. It is definitely an entry level DSLR, but with the right settings and a good tripod, it can produce some acceptable images. The key is the lenses.
I am upgrading to a D7000 or D600 this spring. I can't decide between FX and DX framing. I am leaning more towards the D7000 for it's full HD video and mirror lock up function for still photography. I'm looking at a nice piece of glass for it, but I'll have to drop another 1,000 on top of the 1,000 for the camera (which in consideration of some of the other equipment out there is still on the low to medium end)